Seumas,

I was probably a bit misleading to say regression

is not an estimation technique. The word regression

meaning to revert back to the original, or find the

underlying real equation for a set of data. "Kriging"

is a form of what is called "generalised linear regression"

which is one of the most advanced forms of regression.

The simpler forms of regression can be used to fit

parametrics equations to data, such as linear regression

to fit an equation of a line to a set of data points,

or non-linear regression to fit a polynomial surface

to a scattered set of say topography data points.

Not really estimation, but equation fitting. I use non-linear

regression to fit equations to drillhole survey points

to plot their curves. In it's more advanced form when

you wish to fit equations to say a set of two dimensional

data points, or three dimensional orebody samples,

this is called trend surface fitting. Unfortunately normally

the equations developed from trend surface fitting

become massively too complex to handle to be practical,

and hence estimation is opted for.

Digby